In a manufacturing process for manufacturing semiconductor devices, liquid crystal panels, LEDs, solar cells or the like, a process gas is introduced into a process chamber which is being evacuated to perform various processes such as an etching process, a CVD process or the like. The process chamber for performing several processes such as an etching process, a CVD process or the like is evacuated by a vacuum pump. Further, the process chamber and exhaust apparatuses connected to the process chamber are cleaned periodically by supplying a cleaning gas thereto. Because exhaust gases such as the process gas, the cleaning gas or the like contain a silane-based gas (SiH4, TEOS or the like), a halogen-based gas (NF3, ClF3, SF6, CHF3 or the like), a PFC gas (CF4, C2F6 or the like) or the like, such exhaust gases have negative effects on the human member and on the global environment such as global warming. Therefore, it is not preferable that these exhaust gases are emitted to the atmosphere as they are. Accordingly, these exhaust gases are made harmless by an exhaust gas treatment apparatus provided at a downstream side of the vacuum pump, and the harmless exhaust gases are emitted to the atmosphere.
Heretofore, the vacuum pump and the exhaust gas treatment apparatus are housed respectively in individual housings, and hence they are installed in distant positions and are required to be connected to each other by a connecting pipe. Thus, the vacuum pump and the exhaust gas treatment apparatus have not been an optimum system from the standpoint of saving energy by interchanging necessary heat between the vacuum pump and the exhaust gas treatment apparatus. Therefore, a system comprising a vacuum pump and an exhaust gas treatment apparatus which are accommodated in one housing and connected by a short pipe has been developed, and such system has been sold as an integrated-type exhaust system. However, even in such integrated-type exhaust system, the pipe interconnecting the vacuum pump and the exhaust gas treatment apparatus is several meters long, and is kept warm or heated by a heater or the like for preventing a product generated by gas treatment from being attached to the pipe.
In both of the exhaust system wherein the vacuum pump and the exhaust gas treatment apparatus are housed respectively in individual housings and the exhaust system wherein the vacuum pump and the exhaust gas treatment apparatus are housed in one housing, it is problematic that the heat of the exhaust gas heated by compression beat of the vacuum pump has not been effectively utilized in the exhaust gas treatment apparatus provided at the subsequent stage of the vacuum pump.
Further, in the above exhaust systems, in order to prevent a product from being attached to the interior of the vacuum pump, in some cases, purging by a heated inert gas is performed for the purpose of lowering partial pressure of the product. However, if the inert gas is used without being heated, vapor pressure is also lowered, and thus the product cannot be prevented from being attached to the interior of the vacuum pump. Therefore, it is indispensable to heat the inert gas. In this case, a dedicated heater is necessary for heating the inert gas, and the generated heat is transferred primarily to the surrounding part and the treated gas and is not reused.